Lanefan
Victoria Rules
Barring outside real-life circumstances getting in the way (an equal-opportunity hazard), that's purely by choice of the people involved. Particularly the GM.Except that's not remotely true. It can be true and may be the case if we narrowly restrict our sense of RPGs to your games, but that is FAR from being a universal truth for RPGs. Sorry, but not all tables get "all the time in the world" regardless of the age of the participants. Some will only be one-shots. Some will only be 5-10 sessions. Some may get 20 sessions. There is no "all the time in the world" nonsense in the modern era.
If a game's a one-shot that's because either the GM set it up that way or the collective group chose it'd be that way.
If a game only goes for 20 sessions it's because either the GM set it up that way or because the group in general made that choice.
But if the GM sets it up to be open ended and the players choose to keep coming back then yes, you've got all the time in the world. Enjoy.

Again, barring external real-life circumstances it's a reality imposed only by one's own choices.There are other games that some gamers want to try. There is a competition of attention. I think that most TTRPGs in the modern era lean into this reality instead of pretending that mega-decade campaigns that meet weekly in any way reflect the norm.